The U.S. armed forces have a need to operate, survive and sustain operations safely in chemical and biological hazard environments. The continued proliferation of chemical and biological weapons creates a need to ensure that U.S. forces can successfully complete missions in environments that could become contaminated with chemical and biological agents. Technologies are needed to support the soldier across the spectrum of potential conflicts and contaminant exposures. In addition, other environments, particularly in healthcare facilities, have a need to operate and to sustain operations in areas that are exposed to chemical and biological contaminant challenges on a daily basis.
Current decontamination/cleaning methods for biological and chemical contaminants are laborious and are greatly dependent on the care and attention to detail of cleaning personnel. Traditionally, these methods require the use of hazardous chemicals and generally do not provide long-lasting or ongoing protection. Once a surface has been manually cleaned, new contaminants on the surface can present a threat to the health and safety of those who come in contact it until the next manual cleaning procedure.
In military applications in particular, operational decontamination requires that an object or device be enabled to return to service as rapidly as possible; thorough decontamination enables an object or device to be handled by any user without personal protective equipment. Both operational and thorough decontamination are advantages that may be achieved with reactive coating compositions of the invention.
Reactive coatings have been in development for a number of years with some limited success. Reactive coatings with the capacity to decontaminate smaller areas or articles and/or smaller amounts of chemical and biological agents have been demonstrated. Traditionally, due to limits on the amount of “reactivity” that can be applied to a surface or incorporated into an article, reactive coatings alone are unlikely to have the capacity to effect operational or thorough decontamination of larger surface areas heavily contaminated with chemical or biological warfare agents.
A reactive coating with the ability to reduce, eliminate or neutralize contamination between cleanings provides significant benefits. Most currently available reactive coating technologies are considered “permanent” in the sense that when integrated into a fabric or substrate material or applied to a surface, they remain continuously reactive until fouled by contaminants. At that point, the material or surface usually must be thoroughly cleaned and decontaminated, or removed, disposed of, and replaced.
By contrast, a renewable coating is a two-part system consisting of first, a nonreactive foundation layer that may be either integrated into a substrate or applied as a surface coating, and second, an activation chemistry (liquid or gaseous), or “active”, that renders the foundation layer “reactive” to a contaminant on the surface. The reactivity of a renewable coating may be “recharged” or renewed by reapplication of the active after exposure to chemical and biological contaminants. Ideally, there would be no need to thoroughly clean or decontaminate, remove, dispose of, and replace the foundation layer of a renewable coating.
Renewable coatings, in particular, offer a potential solution to problems typically encountered with traditional reactive surface technologies. These include: fouling from environmental contaminants, limited reactive capacity at the surface and rapid deterioration of the surface from environmental conditions or continuous exposure to contaminants.
In general, chemicals used against biological species and chemical contaminants are classified as “actives” and include without limitation halides, oxidizers, phenols, quaternary ammonium salts, heavy metals, and aldehydes. When higher levels of actives are present and available on the surface, decontamination efficacy will improve. Commercially, actives have been added to surfaces in order to try and create reactive and time-release materials. Two currently available examples are HALOSHIELD, a slow release chlorine-based system for making antimicrobial textiles, and TRIOSYN, a quaternary ammonium triodide coating. HALOSHIELD-treated textiles rely on replacement of chlorine from bleach when being washed.
Attempts to create antimicrobial coatings for surfaces and articles are described in the literature and have met with some limited success. U.S. Pat. No. 7,306,777 is directed to a polyethylene/polyvinyl alcohol copolymer comprising a metal based antimicrobial compositions within the polymer for application to a variety of substrates. The copolymer is not stated to be renewable.
U.S. Pat. No. 7,449,194 is directed to a “body covering” article (such as an apron, gown or glove) that is made from an antimicrobial material. The antimicrobial material comprises a polymer, such as polyolefins, PVC, latex, nitrile, mylar, polyurethane and neoprene; a plasticizer; and an active capable of generating and releasing at least one gas upon exposure to light and/or humidity. The gas is antimicrobial and will retard, control, kill or prevent microbiological contamination of the skin or other surface in contact with the article. The “gas generating” composition includes hydrogen peroxide (0.5-20 wt. %), chlorine dioxide, sulfur dioxide, carbon dioxide and nitrous oxide. The article is not renewable or rechargeable with active.
U.S. Patent Publication No. 2008/0138373 is directed to a protective or cleaning article that has an exterior surface of at least a partial coating or layer of a stabilized peroxide compound and a treatment for protective articles and cleaning articles, such as tissues and gloves. Hydrogen peroxide and other peroxide salts are listed as oxidizing antimicrobials thought to be virucidal as well as bactericidal. Vinyl pyrrolidone copolymers are mentioned as hydrogen peroxide stabilizing agents; however, vinyl pyrrolidone homopolymers are not acceptable because they create stiff films. Preferable vinyl pyrrolidone copolymers are those that do not form films or form only soft films. The treatment is not described as renewable.
U.S. Patent Publication No. US2008/00260026 discloses a “removable” coating comprising a water soluble polymer (that will dry to form a film) and at least one antimicrobial. The composition is described as biocidal and/or biostatic. Polyvinyl alcohols alone or copolymerized with olefins are disclosed. Peroxide and peroxyacids are disclosed as actives, among many other actives disclosed. The coating is not stated to be renewable and may or may not be biocidal.
U.S. Patent Publication No. 2009/0155451 discloses an antimicrobial coating system, comprising a film-forming composition and an antimicrobial. The film-forming composition comprises a polymer and includes an effective amount of an antimicrobial agent dispersed within the polymer. The polymer may be an acrylic, urethane or PVA polymer; the active is selected from fatty acid monoesters, fatty acid monoethers, a transition metal ion-containing compound, a quaternary ammonium compound, a biguanide, or combinations thereof. Peroxides are identified only as fast-acting optional components that do not provide activity over extended periods of time, as compared to the antimicrobial agent. The coating is not renewable.
U.S. Patent Publication No. 2009/0275906 discloses an absorbent article with a thin film layer that includes an active agent. Peroxide is one of the “actives” disclosed. The thin film is polymeric and is layered onto the article using LBL deposition. PVP comprises one of the “layers”, i.e., the second “neutral” layer that is a hydrogen bond acceptor. The “first” layer includes other polymers that are hydrogen bond donors. Claims are directed to the absorbent article, not the film. There is no mention that the absorbent article may be renewed or recharged with active.
U.S. Patent Publication No. 2010/0009011 is directed to a polyurethane-based composition containing crosslinked polymers of heterocyclic N-vinyl monomers (including PVP, 0.1-100% by wt.). The composition is used to make sponges or other objects that release disinfectants over time. Hydrogen peroxide (3-70 wt. %) is one of the potential disinfectants. The publication is concerned with foam based articles and not coatings. The disinfectant activity is not renewable.
WO 2006/135620 is directed to a PVP/hydrogen peroxide complex used to form a gel that is used to deodorize air and surfaces. The active could also be a peroxohydrate compound. The complex relies on release of gas to deodorize air and surfaces. It may be used as a solution, solid, gel, or contained within a device.
The literature shows that while there has been a lot of activity in developing antimicrobial textiles, absorbent sponges, tissues, and other articles, no current reactive surface technology has been developed that has demonstrated efficacy sufficient to decontaminate standard or larger scale interior or exterior chemical or biological challenges, particularly those encountered with chemical and biological warfare agents. No current technologies are available for field military use as a reactive coating. Most activity has surrounded the development of single-use reactive surfaces and articles that must be thoroughly cleaned and decontaminated, or removed, disposed of and replaced after contamination. No current technologies have been demonstrated to be renewable with simple reapplication of the active.
Significant effort has been invested into the creation of reactive surfaces for larger scale commercial and military use with limited progress. Most technologies under development suffer from a variety of performance challenges but most notably the following:                Limited capacity—many technologies have been shown to be biostatic (only prevent growth) under ideal conditions. Many current systems require an extended amount of time (days) before they can fully deal with a realistic level of contamination. Ideally, a reactive surface would provide a very high level of activity against bacteria, viruses, and fungi and even hard to kill spores. Additionally, the ideal system would also reduce the threats from chemical warfare agents or other toxic chemicals.        Cross-contamination—biostatic technologies only protect the surface they are applied to. This approach leaves contaminant available for transfer to any surface or entity that comes into contact. The ideal system would inactivate the biological or chemical contaminant assuring a safe surface between cleaning.        Fouling—a well-known problem for reactive coatings is fouling of the surface by either environmental conditions or residue from the contaminant that has been neutralized. Actives that are available on a clean surface can easily be covered by layers of simple dirt/dust or they can be covered by the residue from decontaminated biologicals or chemicals. An ideal system would be resistant to a reduction in performance resulting from these organic loads.        Practical, multiple use applications—many of the current technologies are designed for specific applications under ideal conditions and are therefore limited in their viability.        
There is, therefore, a need for reactive surface technology that provides biocidal activity and chemical decontamination even in the face of organic load buildup, that is effective against a wide variety of contaminants and that can be applied to a wide variety of surfaces in traditional interior and exterior environments. There is no current consensus as to performance requirements for reactive surface coatings. An ideal system would be applicable to commercial (including medical) and military markets, safe to use and handle, effective against a wide variety of contaminants, applicable to and easily integrated onto or into a wide variety of porous and non-porous surfaces, effective under organic load build-up, and renewable or rechargeable by reapplication of the active. In addition, a useful system would be stable and have extended use life and be flexible in its application, giving the user the option to activate the film in a number of ways using different forms of the active.
A new technology has been developed comprising a reactive surface designed to work in conjunction with current decontamination systems and processes to achieve greater efficacy, or as a stand-alone product to address residual or low levels of agent. This technology surprisingly meets the need for the quick restoration of equipment, vehicles, building and shelter interiors, and essential support functions, such as field based military facilities, hospitals, manufacturing facilities and other facilities exposed to chemical and biological challenges.
A key advantage of this technology aligns with certain military requirements to sustain combat operations through 1) the ability to quickly bring forces back to full operational effectiveness; 2) restoring equipment and vehicles to usable status quickly; and 3) reducing the logistics burden of decontamination operations.
This invention is directed to a reactive surface coating composition that may be incorporated into or onto a surface or material as part of the manufacturing process or applied to an existing material at any point during its life. The surfaces to which this invention can be applied are unlimited. This invention has been demonstrated to be effective when applied to both hard non-porous surfaces and porous surfaces.
The inventive reactive surface compositions are comprised primarily of a hygroscopic polymer or blend of polymers (hereinafter referred to as the polymer) and an active. The ability to modify the physical properties of the inventive reactive surface compositions to tailor them for various purposes is an unexpected and distinct advantage of the invention.
The polymer selected for use in the inventive compositions may have and preferably has a synergistic effect with an active(s), such as, but not limited to, hydrogen peroxide, chlorine, peracetic acid, and the like. This synergistic effect is demonstrated as an increase in biocidal or chemical decontamination activity that is greater than that achieved with either the polymer or the active when used alone. Importantly, upon mixing with or exposure to the active, the selected polymer does not reduce or limit the amount of active available for the application or its efficacy. A preferred polymer is polyvinyl pyrrolidone (PVP, and a preferred active is hydrogen peroxide.
The invention provides for a reactive surface that may be recharged or activated through any process that provides addition of the active to the surface, in the form of a liquid, gas or vapor. The amount of active applied may be varied to achieve different levels of surface activity to tailor the functionality to the desired task.
It is an object of the invention to provide a reactive composition comprising a hygroscopic polymer and an active, for incorporation into articles or application to hard surfaces, which provides biocidal and chemical decontamination/neutralization activity against a large variety of biological and chemical contaminants in a short period of time, including without limitation biological and chemical warfare agents.
It is another object of the invention to provide a reactive composition that has residual activity and maintains its biocidal and chemical decontamination/neutralization activity under organic load and dilution.
It is yet another object of the invention to provide a reactive composition that may be recharged or renewed with an active during use, without the need to remove, dispose of, and replace the reactive composition.
Still another object of the invention is to provide a reactive composition that is safe to handle and environmentally safe and that may be applied to porous and non-porous surfaces alike.